1 



5G4 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the faculty of protective encystinent, if only the suitable conditions 

 could be discovered. 



A precise account is given of the process of encystment in Paramce- 

 cium and Spirostomum ambiguum ; and there are many other detailed 

 observations of interest. 



New Trypanosoma.*— D. Bruce describes T. thcileri sp. n. discovered 

 by A. Theiler in blood taken from a young ox which had just recovered 

 from rinderpest. It is nearly twice as large as the Trypanosoma of 

 Surra, Tse-tse fly disease, or of rat, but agrees with them in its oval 

 protoplasmic body, longitudinal fin-like membrane, and single flagel- 

 lum. 



It only infects cattle ; horses, dogs, goats, rabbits, and guinea-pigs 

 are all immune. "When inoculated into calves it causes an acute perni- 

 cious anaemia with grave blood changes ; or a general anaemia without 

 deformation of the elements of the blood ; or, lastly, only a slight fever, 

 but there is a relative natural immunity in cattle against it. The disease 

 is probably that which Kolle described as bovine malaria. 



Multiplication of Trypanosoma in Fishes, f — A. Laveran and 

 F. Mesnil describe the binary fission (equal or sub-equal) of Trypano- 

 soma remaki and Trypanoplasma borreli in the blood ot fishes, where the 

 presence of these parasites seems only slightly, if at all, pathogenic. 

 They have also shown that these parasites may be readily inoculated 

 from one fish to another of the same species. 



Sexual Phenomena in Pterocephalus.J— L. Leger and O. Duboscq 

 find that in the Gregarine, Pterocephalus nobilis A. Schn., parasitic in 

 Scolopendra, there are sexual elements, as in the Stylorhynchids, differen- 

 tiated as ova and spermatozoa. 



The so-called conjugation is anisogamous in a high degree. But, 

 while in Stylorhynchus the very large spermatozoa bear with them the 

 larger portion of nutritive reserve, those of Pterocephalus are very minute, 

 and the nutritive vitellus is in the ova. 



Sarcocystis tenella in Man.§ — P. Vuillemin has found in prepa- 

 rations made by Hoche conclusive evidence that Sarcocystis tenella, 

 common in the sheep, occurs in man's muscles. He notes that the 

 membrane surrounding the parasite is two layers thick. The external 

 layer is composed of an achromatic, flexible, compressible " fundamental 

 substance," and a stainable substance, disposed in irregular prisms,. 

 simulating a ciliary covering when the fundamental substance is de- 

 stroyed. The units, which are at first quite uniform, become differen- 

 tiated into fertile and sterile forms. 



* Proc. Roy. Soc. London, lxix. (1902) p. 496. 



t Comptes Rendus, exxxiv. (1902) pp. 1405-9. 



% Tom. cit., pp. 1148-9. § Tom. cit., pp. 1152-4. 



